This invention relates to apparatus for treating with a liquid sheets of flexible photographic material having a front side and a reverse side the front side being covered with a light sensitive layer, comprising:
a container,
a vessel therein which is adapted for receiving the liquid therein up to a determined level, and is of generally cylindrical configuration, having a vessel sidewall;
a drivable drum having a cylindrical surface and being rotatable about a substantially horizontal axis, the said liquid level present in the vessel being sufficiently high to immerse, during rotation of the drum, a lower region thereof in the liquid,
guiding means adapted for guiding a sheet of the photographic material into contact with the drum, with the reverse side of the sheet contacting the drum surface; and
rotatable roller means spacedly disposed about the drum surface so that wall sections of the vessel are present between every two consecutive roller means, which roller means keep the said sheet, during its passage about the drum and through the liquid in the vessel, in contact with the drum surface.
In the past photohobbyists and professional photographers who have processed their own prints have had to use processing dishes and have had to continuously or intermittently move the prints in the dish to ensure that the print is processed uniformly. Often development processes require four or five minutes or even longer and fixing times can be just as long. Photographic processing houses who handle hundreds of prints per hour have very long processing tanks through which the prints can be fed to develop or fix the print in the requisite time, the action of passing the print through the solution causing fresh solution to come continuously into contact with the print surface. However it is not practical for a photohobbyist or professional photographer who wishes to process only his own prints to have such a processing machine because its large size is dependent on the length of processing time required and on the rate at which prints are to be processed.
In a number of prior art processing machines are described in patent specifications photographic material is fed through a processing machine in which a drum is rotating in the processing liquid and the photographic material is caused to adhere to the outside of the drum for part of a full rotation only, of the drum in the liquid. Examples of such patent specifications are German Offenlegungsschrift No. 1,497,496 and Offenlegungsschrift No. 2,615,932. However, in such proposed machines the material would not be in contact with the processing liquid for sufficient time for the process to be fully carried out, unless rotating very slowly.
Now, in the German Offenlegungsschrift No. 2,414,824 there is described an apparatus in which photographic films are caused to adhere to the surface of a drum which rotates in processing liquid and to rotate with the drum for sufficient length of time for the process to be completed. It is said in Offenlegungsschrift No. 2,414,824 that knives set at an acute angle at a predetermined distance from the surface of the drum have been used to strip-off the photographic film from the surface of the drum but the use of such knives has not been entirely successful. Offenlegungsschrift No. 2,414,824 proposes that a jet of processing liquid issuing from a knife shaped device is used to strip the film from the processing drum. Such a liquid jet is a complicated and expensive device which is satisfactory for a large processing apparatus, but which is inappropriate for a simple processing apparatus suitable for use by a photohobbyist or a professional photographer who wishes to process only his own prints.